Hi All,
I had recently faced issue with one of the Linux VM , wherein RDM UUID got changed after issue with RDM and the other team member removed and re-added the RDM to the VM after rebooting.
Since We had created ASM disk through RDMs LUN , change in UUID resulted in issue with the disks.
As a part of troubleshooting to get to the cause of issue i went through below:
Original UUID of RDM which is attached to all the hosts inside the cluster:
LUN Name Size scsi_id UID
VM_TEST1 100GB 25 naa.6005076801808529E80000000000065A
Case1:
Presented RDM to VM in Virtual Compatibility Mode.
UUID visible inside the Linux VM to be used for creation of ASM disk
/dev/sdb 36000c29e964d6e0742cd608c8db506b3
Test 1: Unmapped the RDM, migrated VM to other host and then again remap RDMs on second host
Result: UUID got changed
/dev/sdb 36000c290b08f97b00ed91854b3d9b818
Test 2: VMotion of VM
Result: no change in UUIDs
/dev/sdb 36000c290b08f97b00ed91854b3d9b818
Test 3: sVMotion of VM with attached RDM
Result: UUID got changed
/dev/sdb 36000c29b33185c6467ab6323d2e36dd4
Case2:
Presented RDM to VM in Physical Compatibility Mode.
Test 1: VMotion of VM
Result: No change in the UUID
/dev/sdb 36005076801808529e80000000000065a
Test 2: Unmapped the RDM, migrated VM to other host and then again remap RDMs on second host
Result: No change in the UUID
/dev/sdb 36005076801808529e80000000000065a
Test 3: sVMotion of VM with attached RDM
Result: No change in the UUID
/dev/sdb 36005076801808529e80000000000065a
Here, in conclusion i can say , UUID get changed if we add RDM in Virtual Mode whereas in case of Physical Mode regardless of any action been performed on live server no changes to the RDM UUID will be there.
Now i have had added RDM in Physical Mode(though i know i cannot take snapshot), apart from that VM is working fine since then.
Please provide your feedback on this.
